Crop and Pest Management Guidelines

A Cornell Cooperative Extension Publication

7.11 Going Spraying! Mixing Procedures

 7.11 Going Spraying!


Mixing Procedures

Safety and the Law

  • Always remain alert; pesticides are potentially dangerous to the operator and the environment.
  • Tractors and sprayers are dangerous machines and care should be taken when operating them.
  • Always follow Federal and State laws concerning licensing of operators and handling, application and disposal of pesticides.

Always read the label for detailed application information and keep a record.


The seven P's of machinery management.

Proper prior planning prevents poor performance.

  • Fill the tank on level ground per label instructions. If none are given, fill the tank half full with clean water.

  • Prime the pump with water, if needed.





  • Make sure there is no direct connection between the water source and sprayer tank. Direct connections can contaminate the supply by allowing chemicals to siphon back.
  • Use a strainer when using water from a stream or pond.


  • When opening a package:
    •  Avoid using an "implement"; if used, decontaminate after use.
    •  Avoid splashing and "glugging" of liquid formulations.
  • Always add concentrated pesticides to a partially filled tank.
  • If adding more than one product, do so separately and in the recommended order. NEVER mix them together in their concentrated forms
  • If available, add product through a low-level induction bowl or through a suction probe.
    •  If not available, add pesticides through the tank filter basket, except for soluble packs and some water dispersible granule formulations. Some wettable powders may need to be premised.


  • Accurately measure the calculated amount of product.
    •  Weigh solid formulations, and measure out liquid formulations, unless they come in pre-weighed packages appropriate for the spraying area.
    •  Handle water soluble packages according to directions. Keep packs dry and do not force open the packs.


  • If foaming is likely:
    •  Fill the tank three-quarters full of water and use gentle agitation.
    •  Add the pesticide.
    •  Add the surfactant.
    •  Continue to use gentle agitation until filling is finished.
    • Do not add water from a height.

  • Triple rinse pesticide containers with clean water and put washings into the tank.
  • Rinse off any pesticides spilled on the sprayer or container, and avoid contaminating the surroundings or yourself.

  • Fill tank to the correct level and agitate while filling. Continue agitating while driving to the field and whilst spraying unless instructions advise otherwise. If spraying is delayed, agitate thoroughly just before use.

  • Rinse impermeable protective clothing (rubber boots, gloves, etc.) with clean water after use.

  • Remove other protective clothing and store before getting into tractor cab.

  • Seal unused chemicals and store in a safe location.

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